Add option to use mat-label instead of placeholder

[trentjones21]

Is your feature request related to a problem? Please describe. Angular Material form fields now need a mat-label instead of (or along side) a placeholder.

Describe the solution you'd like To be able to include the mat-label text in the options, instead of just the placeholder text.

Additional context Here is a stackblitz that demonstrates the problem https://stackblitz.com/edit/angular-t1tl2t